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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Synthesis of Bio-Based Polymers Containing D-Isosorbide by Ring-Opening Metathesis Polymerization

Yalamanchili, Chinni 17 May 2014 (has links)
The utilization of renewable sources as alternatives for petroleum and natural gas products has immense commercial, health and global warming significance. D-Isosorbide (2) is a bifunctional, polar, chiral and rigid molecule, which is produced from renewable sources. Synthesis of new polymers containing 2 is of interest for polymers and in drug delivery. The aim of the present work is to synthesize various polymers (homo- and copolymers) containing 2 via the olefin metathesis routes, ring-opening metathesis polymerization (ROMP) and acyclic-diene metathesis polymerization (ADMET). N-Phenyl-7-oxanorbornene-dicarboximide, and norbornene functionalized onto 2 were used as the monomers for ROMP. These monomers were polymerized using Grubbs’ catalysts to generate a series of homo-, co-, block and cross-linked-polymers. These polymers were characterized using GPC, NMR, and IR. In addition, ADMET polymerization of a terminal diolefinunctionalized D-isosorbide (2) was also conducted to produce ADMET polymers.
42

Generalized Predictive Control Parameter Adaptation Using a Fuzzy Logic Approach

Lloyd, John William 09 November 2011 (has links)
A method to adapt the Generalized Predictive Control parameters to improve broadband disturbance rejection was developed and tested. The effect of the parameters on disturbance rejection has previously been poorly understood and a trial and error method was used to achieve adequate results. This dissertation provides insight on the effect of the parameters, as well as an adaptive tuning method to adjust them. The study begins by showing the effect of the four GPC parameters, the control and prediction horizons, control weighting &lambda , and order, on the disturbance rejection and control effort of a vibrating plate. It is shown that the effect of increases in the control and prediction horizon becomes negligible after a certain point. This occurs at nearly the same point for a variety of &lambda 's and orders, and hence they can be eliminated from the tuning space. The control effort and closed-loop disturbance rejection are shown to be highly dependant on &lambda and order, thereby becoming the parameters that need to be tuned. The behavior is categorized into various groups and further investigated. The pole and zero locations of the closed-loop system are examined to reveal how GPC gains control and how it can fail for non-minimum phase plants. A set of fuzzy logic modules is developed to adapt &lambda with order fixed, and conversely to adapt order with &lambda fixed. The effectiveness of the method is demonstrated in both numerical simulations and laboratory experiments. / Ph. D.
43

Caractérisation moléculaire et élémentaire des produits pétroliers lourds / Molecular and elemental characterization of heavy petroleum products

Desprez, Alain 19 November 2014 (has links)
Les pétroles utilisés en raffinage étant de plus en plus lourds et chargés en métaux et hétéroélements, il est d’une grande importance pour les activités de raffinage de connaître la spéciation de ces espèces au sein des produits pétroliers et leurs comportements durant les procédés de raffinage. Afin d’apporter des réponses à cette problématique des techniques de caractérisation élémentaire et moléculaire ont été utilisées notamment par ICP MS Haute Résolution et FT ICR MS respectivement. Ces techniques analytiques sont appliquées à différents échantillons pétroliers provenant parfois de procédés de raffinage et les informations obtenues au niveau élémentaire et moléculaire sont utilisées de manières complémentaires pour améliorer notre compréhension des mécanismes se produisant au sein de nos échantillons durant les activités de raffinage. / The crude oils available for the refining industry are heavier and heavier and more concentrated in metals and heteroelements. It is thus of great importance to study the speciation of these species within the petroleum products and their behavior during the refining processes. To answer that problematic, elemental and molecular characterization techniques have been used, mainly High Resolution ICP MS and FT ICR MS for the elemental and molecular characterization respectively. The analytical techniques quoted are used for the analysis of several petroleum products sometimes originating from refining processes and the information obtained at the elemental and molecular level are combined to improve our understanding of the mechanisms occurring within our samples during refining activities.
44

Effets de la consommation de l’alpha-glycérylphosphorylcholine sur la performance physique chez des joueurs (ses) de volleyball universitaire.

St-Arnaud, Samuel 04 1900 (has links)
No description available.
45

Functional Dendritic Materials using Click Chemistry : Synthesis, Characterizations and Applications

Antoni, Per January 2008 (has links)
Förfrågan efter nya och mer avancerade applikationer är en pågående process vilket leder till en konstant utveckling av nya material. För att förstå relationen mellan en applikations egenskaper och dess sammansättning krävs full förståelse och kontroll över materialets uppbyggnad. En sådan kontroll över uppbyggnaden hos material hittas i en undergrupp till dendritiska polymerer som kallas dendrimerer. I den här doktorsavhandlingen belyses nya metoder för att framställa dendrimer med hjälp av selektiva kemiska reaktioner. Sådana selektiva reaktioner kan hittas inom konceptet klickkemi och har i detta arbete kombinerats med traditionell anhydrid- och karbodiimidmedierad kemi. Denna avhandling diskuterar en accelererad tillväxtmetod, dendrimerer med inre och yttre reaktiva grupper, simultana reaktioner och applikationer baserade på dessa dendritiska material. En accelererad tillväxtmetod har utvecklats baserad på AB2- och CD2-monomerer. Dessa monomerer tillåter tillväxt av dendrimerer utan att använda sig av skyddsgruppkemi eller aktivering av ändgrupper. Detta gjordes genom att kombinera kemoselektiviteten hos klickkemi tillsammans med traditionell syraklorid kopplingar. Dendrimerer med inre alkyn- eller azidfunktionalitet syntetiserades genom att använda AB2C-monomerer. Den dendritiska tillväxten skedde med hjälp av karbodiimidmedierad kemi. Monomererna som användes bär på en C-funktionalitet, alkyn eller azid, och på så sätt byggs får interiören i de syntetiserade dendrimeren en inneburen aktiv funktionell grupp. Ortogonaliteten hos klickkemi användes för att sammanfoga monomerer till en dendritisk struktur. Traditionell anhydridkemi- och klickemireaktioner utfördes samtidigt och på så sätt kunde dendritiska strukturer erhållas med färre antal uppreningssteg. En ljusemitterande dendrimer syntetiserades genom att koppla azidfunktionella dendroner till en alkynfunktionell cyclenkärna. Europiumjoner inkorporerades i kärnan varpå dendrimerens fotofysiska egenskaper analyserades. Mätningarna visade att den bildade triazolen hade en sensibiliserande effekt på europiumjonen. Termiska studier på några av de syntetiserade dendrimerer utfördes för att se om några av dem kunde fungera som templat vid framställning av isoporösa filmer. / The need for new improved materials in cutting edge applications is constantly inspiring researchers to developing novel advanced macromolecular structures. A research area within advanced and complex macromolecular structures is dendrimers and their synthesis. Dendrimers consist of highly dense and branched structures that have promising properties suitable for biomedical and electrical applications and as templating materials. Dendrimers provide full control over the structure and property relationship since they are synthesized with unprecedented control over each reaction step. In this doctoral thesis, new methodologies for dendrimer synthesis are based on the concept of click chemistry in combination with traditional chemical reactions for dendrimer synthesis. This thesis discusses an accelerated growth approach, dendrimers with internal functionality, concurrent reactions and their applications. An accelerated growth approach for dendrimers was developed based on AB2- and CD2-monomers. These allow dendritic growth without the use of activation or deprotection of the peripheral end-groups. This was achieved by combining the chemoselective nature of click chemistry and traditional acid chloride reactions. Dendrimers with internal azide/alkyne functionality were prepared by adding AB2C monomers to a multifunctional core. Dendritic growth was obtained by employing carbodiimide mediated chemistry. The monomers carry a pendant C-functionality (alkyne or azide) that remains available in the dendritic interior resulting in dendrimers with internal and peripheral functionalities. The orthogonal nature of click chemistry was utilized for the simultaneous assembly of monomers into dendritic structures. Traditional anhydride chemistry and click chemistry were carried out concurrently to obtain dendritic structures. This procedure allows synthesis of dendritic structures using fewer purification steps. Thermal analyses on selected dendrimers were carried out to verify their use as templates for the formation of honeycomb membranes. Additionally, a light emitting dendrimer was prepared by coupling of azide functional dendrons to an alkyne functional cyclen core. A Europium ion was incorporated into the dendrimer core, and photophysical measurements on the metal containing dendrimer revealed that the formed triazole linkage possesses a sensitizing effect. / QC 20100629
46

Mechatronic design under uncertainties

Zhang, Kai 22 October 2013 (has links) (PDF)
Flexible structures are increasingly used in various applications such as aerospace, automotive and so on. Since they are lightly damped and susceptible to vibrations, active vibration control is desirable. In practice, in addition to achieving effective vibration reduction, we have also to consider the required control energy to avoid the energy insufficiency, the control input to avoid control saturation and reduce the effects of measurement noises. On the other hand, as flexible structures have infinite number of resonant modes and only the first few can be employed in the system modeling and the controller design, there always exist neglected high-frequency dynamics, which can induce the spillover instability. Furthermore, the parametric uncertainties on modal parameters can degrade the control performances and even destabilize the closed-loop system. In this context, a quantitative robust control methodology for active vibration control of flexible structure is proposed in this thesis. Phase and gain control polices are first proposed to enforce frequency-dependent phase and gain requirements on the controller, which can be realized by the output feedback H1 control design. The phase and gain control polices based H1 control can make a trade-off among the complete set of control objectives and offer a qualitative robust controller. Especially, the LPV H1 control is used to reduce the required control energy for LPV systems. The generalized polynomial chaos (gPC) framework with finite element analysis is employed for uncertainty quantification. It allows us to investigate the effects of structural property uncertainties on natural frequencies and achieve their probabilistic information. Then, in the presence of parametric and dynamic uncertainties, µ / v analysis and the random algorithm using Monte Carlo Method are used to quantitatively ensure the closed-loop stability and performance robustness properties both in deterministic and probabilistic senses. The proposed quantitative robust control methodology is thus developed by employing various techniques from automatic control and mechanical engineering, thus reducing the gap between them for robust vibration control of flexible structures. Its effectiveness are verified by numerical simulations and experimental validation on LTI and LPV non-collocated piezoelectric cantilever beams.
47

The influence of acid and direct azo dyes and their intermediates on the degradation of wool keratin : the characterisation by yarn strength measurements of the degradation of wool under conditions relevant to dyeing and of the keratin degradation products, by fractionation, electrophoresis and amino acid analysis

McComish, John January 1981 (has links)
The degradation of wool keratin under conditions relevant to those of wool dyeing was investigated using the techniques of gel permeation chromatography (GPC), ion exchange gel chromatography, and amino acid analysis. Physical testing of the treated and untreated wool was also carried out to determine the physical changes occurring, parameters used being percentage elongation at the break, and the breaking strain of the fibre. Samples of wool keratin were immersed in various aqueous solutions at 1000C for 24 hours and the filtered, aqueous, oxidised extracts were analysed* The solutions used varied only in the dye, or dye intermediate present in the treatment solution. All treatment baths contained 10% owf 1.02 x 10 -2 MSulphuric VI acid; 10%owf 7.04x 10 -3 MSodium sulphate VI ; A 100 :1 liquor ratio was used in each case. Some of the dye intermediates showed a marked catalytic effect, particularly in their effect on breaking strain, a decrease of 40% in some cases. The GPC profiles of the extracted proteins were examined in detail and compared against previous workers' results. An explanation of the behaviour of the dyes and intermediates was proposed. The amino acid composition data of the extracted and fractionated proteins were compared against various morphological components extracted by other workers, as was the total gelatin obtained from each treatment.
48

Mechatronic design under uncertainties / Conception mécatronique en présence des incertitudes

Zhang, Kai 22 October 2013 (has links)
Les structures flexibles sont de plus en plus utilisées dans des domaines variés comme l'aérospatiale, l'automobile, etc. Les avantages du contrôle actif des vibrations sont son faible amortissement et sa sensibilité aux vibrations. Dans la réalité, en plus des exigences de réduction effective des vibrations, il faut également prendre en compte la quantité d'énergie nécessaire pour le contrôle, les entrées du contrôle pour éviter la saturation de commande, ainsi que la réduction des effets des bruits de mesure. D'autre part, comme les structures flexibles ont une infinité de modes de résonance et que seuls les premiers modes peuvent être utilisés dans la modélisation du système et dans la conception de contrôleur, les dynamiques négligées en hautes fréquences peuvent induire une instabilité dite "spill over". De plus, les incertitudes sur les paramètres modaux peuvent dégrader les performances de contrôle et même déstabiliser le système en boucle fermée. Dans ce contexte, on propose dans cette thèse une méthodologie quantitative de contrôle actif et robuste des vibrations des structures flexibles. Des stratégies de contrôle de la phase et du gain sont d'abord proposées pour assurer des spécifications dépendant de la fréquence sur la phase et le gain du contrôleur. Ces spécifications peuvent être réalisées par la conception du contrôleur par la méthode Hoo . Le contrôle H00 basé sur ces stratégies permet d'obtenir un compromis entre l'ensemble des objectifs de contrôle et d'offrir un contrôleur robuste qualitatif. En particulier, nous avons utilisé le contrôle LPV Hoo pour réduire l'énergie nécessaire au contrôle du système LPV. Le cadre généralisé du chaos polynomial (gPC) avec analyse par éléments finis, qui permet l'étude des effets des incertitudes de propriétés structurelles sur les fréquences naturelles et qui permet d'obtenir leurs informations probabilistes, est employé pour la quantification des incertitudes. Ensuite, en présence des incertitudes paramétriques et dynamiques, nous avons utilisé l'analyse 11/v et l'algorithme aléatoire en utilisant la méthode de Monte-Carlo pour assurer en même temps la stabilité en boucle fermée et les propriétés de robustesse de la performance à la fois dans le sens déterministe et le sens .probabiliste. La méthodologie de contrôle robuste quantitatif proposée est donc développée en employant des techniques diverses du contrôle automatique et du génie mécanique, et ainsi permet de réduire l'écart entre eux pour le contrôle robuste de la vibration pour des structures flexibles. Son efficacité est vérifiée par des simulations numériques et la validation expérimentale sur des poutres équipées de piézoélectriques non-colocalisés, LTI et LPV. / Flexible structures are increasingly used in various applications such as aerospace, automotive and so on. Since they are lightly damped and susceptible to vibrations, active vibration control is desirable. In practice, in addition to achieving effective vibration reduction, we have also to consider the required control energy to avoid the energy insufficiency, the control input to avoid control saturation and reduce the effects of measurement noises. On the other hand, as flexible structures have infinite number of resonant modes and only the first few can be employed in the system modeling and the controller design, there always exist neglected high-frequency dynamics, which can induce the spillover instability. Furthermore, the parametric uncertainties on modal parameters can degrade the control performances and even destabilize the closed-loop system. In this context, a quantitative robust control methodology for active vibration control of flexible structure is proposed in this thesis. Phase and gain control polices are first proposed to enforce frequency-dependent phase and gain requirements on the controller, which can be realized by the output feedback H1 control design. The phase and gain control polices based H1 control can make a trade-off among the complete set of control objectives and offer a qualitative robust controller. Especially, the LPV H1 control is used to reduce the required control energy for LPV systems. The generalized polynomial chaos (gPC) framework with finite element analysis is employed for uncertainty quantification. It allows us to investigate the effects of structural property uncertainties on natural frequencies and achieve their probabilistic information. Then, in the presence of parametric and dynamic uncertainties, µ / v analysis and the random algorithm using Monte Carlo Method are used to quantitatively ensure the closed-loop stability and performance robustness properties both in deterministic and probabilistic senses. The proposed quantitative robust control methodology is thus developed by employing various techniques from automatic control and mechanical engineering, thus reducing the gap between them for robust vibration control of flexible structures. Its effectiveness are verified by numerical simulations and experimental validation on LTI and LPV non-collocated piezoelectric cantilever beams.
49

Ocenění společnosti Plzeňský Prazdroj, a.s. / Valuation of Plzeňský Prazdroj, a.s.

Varga, Matúš January 2016 (has links)
This master thesis is concerned with the estimation of the market value of equity of Plzeňský Prazdroj, a.s. as at 30 September 2016. The market approach has been selected as the primary valuation approach with the largest impact on the value estimation; specifically the guideline public company method and the comparable transactions method are employed. The income approach based on the DCF Entity method verifies the value conclusion derived from the market approach. The going concern premise is supported by thorough analyses concerning the relevant market; market position of the valued company in relation to its competitors; and its financial health. The thesis concludes a clearly defined and justifiable range of value.
50

Investigation into non-aqueous remedial conservation treatments for iron-tannate dyed organic materials

Wilson, Helen Louise January 2013 (has links)
Iron-tannate dyes have been used for thousands of years and on many continents to colour materials that are now part of our cultural heritage shades of black, grey, or brown. Cellulosic and proteinaceous yarns and woven textiles have been dyed with iron-tannate dyes to form objects or components of objects for domestic and ceremonial use. Unfortunately, the longevity and useful lifetime of iron-tannate dyed objects is threatened by the dye itself which accelerates the degradation of organic materials through metal-catalysed oxidation and acid-catalysed hydrolysis. The accelerated degradation causes weakening, discolouration, and embrittlement of the organic materials at a faster rate than undyed equivalents and if left unimpeded, weakens the objects to the point that they are no longer able to be exhibited without damage. In some cases the degradation is so great that the dyed areas of the objects have crumbled to dust. At present there is no suitable chemical stabilisation method available with which to inhibit this degradation. An aqueous treatment is available for successfully stabilising paper containing iron gall ink; iron gall ink is chemically similar to iron-tannate dye. However, the aqueous nature of this treatment makes it unsuitable for weakened fibres, water soluble components, and water sensitive materials which may be part of a composite material containing iron-tannate dye. Non-aqueous treatments are therefore urgently needed in order to preserve our iron-tannate dyed cultural heritage for future generations.In this project a range of non-aqueous antioxidants and a non-aqueous deacidifier (described in Chapter 8) were tested alongside existing aqueous treatment in order to establish their ability to slow down the degradation of a range of model iron-tannate dyed textiles (Chapters 9 and 10). Model textiles were developed as part of the project (Chapters 3-5) to be substitutes for historic materials in these stabilisation studies. Validation of the model textiles for this purpose (Chapter 6) involved the comparison of the model textiles with selected historic iron-tannate dyed objects within the British Museum’s collection (Chapter 6). The historic objects and the properties of the model textiles before and after accelerated ageing (Chapters 5 and 6) and before and after treatment application (Chapters 9 and 10) have been characterised using a variety of analytical techniques (Chapter 2). In order to determine which accelerated ageing conditions were the most suitable for this project various combinations of elevated temperature and either cycling or stable relative humidity were tested for their ability to produce noticeable changes in the properties of the dyed model textiles within four weeks of ageing (Chapter 7). This project is an AHRC/EPSRC funded Science and Heritage Programme PhD in which the British Museum has been a collaborative institution. Among other wider dissemination methods, research from this project has been presented to the public on numerous occasions at gallery tours and Science Day events at the British Museum.

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